in which, coiled up in a spiral, are little bodies thick at one end and tapering off to the other, where a number of cilia are developed. These bodies are the antherozoids (i.)

The archegonia (e) are cylindrical in shape, with an opening at the top; this opening extends as a central cavity to the base of the cylinder, which is occupied by a large cell, called the embryo-cell (e, 2). Into this cell the antherozoids, when set free, are propelled by their cilia, the protoplasm mingles with that of the embryo-cell, and the fertilisation of the fern is effected. As the result of the fertilisation the embryocell divides into four cells, two above and two below. The two lower ones again divide and subdivide until it assumes a plug-shape and enters into the substance of the prothallus. The two upper cells give rise, one to the stem, or rhizome, of the new fern, and the other to its first rootlet. Professor Huxley thinks it probable "that the plug-like mass absorbs nutritive matter from the prothallus, and supplies the rhizome of the young fern, until it is able to provide for itself." The rhizome now grows, and sends up delicate little fronds (g), and the prothallus, having no further office to serve, gradually shrivels up and vanishes.

Such are the phenomena connected with the reproduction of ferns, and it should be remarked that the fern is not directly the product of the spore. ferns, as in many other plants, there is here exhibited what is known as the "alternation of generations." The spore produces, not a fern like that it was produced by, but an organism closely resembling the more lowly Liverworts-the prothallus. This pro

thallus develops reproductive organs which, instead of producing other prothalli, give rise to a true fern like that which produced the spore. In this lies its chief difference from a seed, for a seed produces a plant. exactly resembling that which produced the seed.

And now it grows vigorously and sends up frond after frond, until the stem becomes thick and the fronds long and spreading, and bear upon their undersurface spore clusters, like those we have before alluded to. These spores afford the surest method to the tyro for detecting ferns, as no other plants produce spores in the same manner. The leafy portion of the fern is known as a frond, but it differs considerably from the leaves of flowering plants. In the latter the point, or apex, of the leaf is first formed, the leaf-stalk last. In the fern the leaf-stalk is formed first, and the apex the last.

If we examine a growing plant of the Common Bracken-fern (Pteris aquilina) we shall find it to consist of an underground creeping stem giving off rootlets below and fronds above. In this case the stem is called a rhizome, because of its creeping underground, but if we take the Common Male-fern (Lastrea filix-mas) we shall find that the stem, instead of taking a horizontal direction, as in Bracken, is perpendicular, and the upper end is above the ground. In this case the stem will be termed a caudex, and a more noticeable example of it will be found in the arborescent stems of the Tree-fern of Australia, &c. It should be noticed that the fronds arise, not from the growing point of the stem, but from certain points at a greater or lesser distance

from it. Along the rhizome of the Bracken-fern, on each side, there runs a line, paler in colour than the rest of the stem, and it is from these lines the fronds take their origin. In the Common Polypody (fig. 97),

which also has a creeping rhizome, the fronds are produced indifferently from the sides or the upper surface. This species, instead of creeping underground, like the Bracken, traverses the surface, and to afford it

sufficient protection it is densely covered with thick brown scales. The point from which a frond is given. off is called a node, the space between two nodes

FIG. 98.

is an internode, and it will be noted that in the Bracken and Polypody these nodes are at irregular distances from each other. But if we examine a

species possessing a vertical stem, as the Male-fern, we shall find the nodes to be pretty equally distanced, though thickly crowded together.

The frond consists of a stipes, a rachis, pinna, pinnules, and lobes. The stipes and rachis constitute what, in popular language, would be called the stalk. The stipes is that part which extends from the base to the leafy portion, where the rachis commences and extends thence to the apex of the frond. The leafy portion in the different species exhibits the utmost variety, from a simple strap-shape as in the Hart'stongue, to the most delicate lace-like arrangement. In the Common Polypody the frond is simply divided into lateral lobes (pinnæ), and a similar division is seen in the Hard-fern, Maidenhair Spleenwort (fig.98), and the Scaly Spleenwort (fig. 99), though between each of these there is considerable variety. In the Male-fern a further division is seen, the pinnæ being subdivided into pinnules; whilst in well-grown specimens of the Bracken the frond is still further subdivided, and termed "decompound."

even

But the varieties of fronds are very numerous, individuals of the same species often differing considerably among themselves. But all are beautiful, and the very types of gracefulness. Thoreau says: "Nature made ferns for pure leaves, to show what she could do in that line." What can be found in Nature more delicate and fresh than the frond of a Lady-fern? Its delicate appearance does not belie its nature, for, excepting the Filmy-ferns, there is none so fragile. Its slender, almost transparent stalk is very succulent, and if the roots be not liberally